Corrugated pipe, such as corrugated metal pipe, is used in various civil engineering applications, such as in culverts, stormwater storage systems, and sewers, both storm and sanitary. These pipes are flexible and use structural bedding and backfill to maintain ring compression (shape). Properly installed, the compressed ring permits live and dead loads to be distributed into the surrounding backfill and thus relieve some of the load on the pipe wall. The combination of corrugation size, metal type, thickness, and backfill type and compaction in these pipe installations provide increased strength over rigid pipes, permitting them to be buried at substantially greater depths with negligible deflection.
However, as with rigid pipe, corrugated metal pipe tends to wear, especially in the invert where the structure is exposed to constant or high velocity waters, corrosive runoff, and/or abrasive flows. Corrugated metal pipe used in applications listed above are also often made of either aluminum or steel with optional protective coatings such as zinc (galvanized), zinc and asphalt, zinc and polymer, or aluminum/steel alloy. All types and coating combinations, however, tend to corrode or abrade over time. As a result of this erosion/corrosion cycle, perforations eventually form in the pipe's invert. Such voids may extend through the pipe and thereby expose the structural bedding and backfill to erosion, scour, and undermining. This cycle creates substantial cavities around the pipe exterior. As erosion of the bedding and backfill continues, soil begins to migrate from the surrounding area through the perforations. The initial clue that soil is infiltrating the pipe is a sinkhole. The continued loss of structural bedding and backfill, and growing cavities around the pipe exterior, will lead to localized wall buckling and, if left unchecked, will eventually lead to critical deformation and ultimate collapse. Corrugated metal pipes structurally need good, well-compacted backfill for support. The loss of that support affects the overall structural capacity of the pipe.
Materials such as crushed stone or walnut shell may be delivered under the corrugated metal pipe where the bedding has eroded to stabilize that area. However, such materials as delivered with current means may not reach many of the cavities in the ground that are small or a significant distance from the point the materials are delivered. The walnut shell may also rot, destabilizing the areas in which it is disposed.
Further, with corrugated metal pipe used in applications involving most storm waterways, water quality standards set by government agencies dictate that an environmentally friendly non-invasive repair system be used.
Accordingly, there may be a need for a corrugated metal pipe repair system and method that delivers a stronger material that is yet environmentally safe to fill voids in the pipe and/or cavities around the pipe, thereby redeeming the structural bedding and backfill zones. There may also be a need for a corrugated metal pipe repair system and method that delivers such a material over a wider area than do traditional systems and can infiltrate remote areas.